Recent heavy duty tires mounted on trucks, buses, and the like maintain the shape of the tread portion due to the tires having a low aspect ratio while having a circumferential reinforcing layer disposed in the belt layer. The circumferential reinforcing layer is a belt ply having a belt angle that is substantially 0° with respect to the circumferential direction of the tire, and is disposed so as to be layered on a pair of cross belts. The technologies disclosed in Japanese Patent Nos. 4642760, 4663638 and 4663639, as well as in Japanese Unexamined Patent Application Publication (translation of PCT application) No. 2012-522686, are conventional pneumatic tires that are configured in this manner.
One problem to be addressed in pneumatic tires is the improvement of braking performance when traveling on wet road surfaces.